In recent years, as the electronic devices are asked to be smaller and thinner, the electronic components equipped in these electronic devices are also required to be downsized. Especially, with the need for thin household device, as a laminated ceramic capacitor has a limited mounting area, the downsized component is required to have a high capacitance.
On the basis of such a market demand, a laminated ceramic capacitor must have a big capacitance and a small size. Here, the electrostatic capacitance of the laminated ceramic capacitor is represented by formula 1.
                    C        =                              (                                                            ɛ                  r                                ×                                  ɛ                  0                                ×                S                            d                        )                    ×          n                                    [                  Formula          ⁢                                          ⁢          1                ]            
C: electrostatic capacitance; εr: relative permittivity; ε0: vacuum permittivity
S: overlapping area of internal electrodes; d: thickness of dielectric ceramic layer; n: number of laminated layers
As the downsizing is highly demanded, the shape and the size of the laminated ceramic capacitor as well as the overlapping area of the internal electrodes are almost fixed. It can be seen from formula 1 that in order to increase the electrostatic capacitance of the laminated ceramic capacitor, adjustments can be made to increase the inherent relative permittivity of the ceramic material, decrease the thickness of the dielectric ceramic layer and also that of the internal electrode layer and increase the number of layers to be laminated.
However, as the relative permittivity is an inherent value depending on the substance, it will not increase to a large extent if no new dielectric material is discovered. Thus, the thickness of the internal electrode layer or the thickness of the dielectric ceramic layer will definitely need to be decreased. Therefore, the laminated ceramic capacitor is required to be formed by internal electrode layers and dielectric ceramic layers with a thickness of 0.60 μm or less.
Usually, in order to get the internal electrode layer and the dielectric ceramic layer thinner, the metal particles forming the internal electrode layer and dielectric ceramic particles forming the dielectric ceramic layer should be micronized powders.
However, if the micronized metal particles and dielectric ceramic particles are used, the reactivity of the metal particle is higher than that of the dielectric ceramic particle, and thus a big mismatch will generate at the temperature where contraction due to sintering begins. As a result, a structure is likely to appear that the internal electrode layer is introduced into the interior of the component main body and voids are generated between the internal electrode layer and the external electrode. In this way, the connection may not good and it is hard to guarantee the quality.
Therefore, Patent Document 1 has proposed a method in which the external electrode is formed directly by plating. In particular, with such a method, a plating film will also be disposed by using the exposure part of the end face of the internal electrode layer as the core even if the internal electrode layer is introduced into the interior of the component main body. As the plating film grows, the exposure parts of the internal electrode layers will connect to each other with the dielectric ceramic layers interposed thereamong so that the external electrode can be formed to be thin and flat.
In addition, Patent Document 2 has disclosed that a structure in which the poor connection between the internal electrode layer and the external electrode layer can be improved can be provided by performing a process where a ceramic element body with the end portion of the internal electrode introduced to the surface is prepared, a process where a resin electrode layer containing a first metal filler and a second metal filler is formed with the first metal filler having a first metal component and the second metal filler having a second metal component with a melting point higher than that of the first metal component, and a heating process where the electrode layer is heated to form an electrode which contains the first and the second metal components and the metal contained in the internal electrode and also has a metal layer on the surface of the ceramic element body.